🧩 solutions

Collection of my solutions to coding problems — with source code and explanation. Currently only solving on LeetCode.

• All Solutions
• Solutions By Category
  • Array
  • String
  • Map
  • Set
  • Stack
  • Queue
  • Deque
  • Linked List
  • Priority Queue
  • Heap
  • Tree
  • Binary Tree
  • Binary Search Tree
  • Depth-First Search
  • Breadth-First Search
  • Math
  • Dynamic Programming
  • Greedy
  • Binary Search
  • Sort

All Solutions

LeetCode

Problem ID	Solution	Problem Specs
1	Two Sum	⇨
2	Add Two Numbers	⇨
3	Longest Substring Without Repeating Characters	⇨
12	Integer to Roman	⇨
13	Roman to Integer	⇨
20	Valid Parentheses	⇨
23	Merge k Sorted Lists	⇨
32	Coin Change	⇨
35	Search Insert Position	⇨
49	Group Anagrams	⇨
55	Jump Game	⇨
66	Plus One	⇨
69	Sqrt(x)	⇨
94	Binary Tree Inorder Traversal	⇨
100	Same Tree	⇨
101	Symmetric Tree	⇨
102	Binary Tree Level Order Traversal	⇨
104	Maximum Depth of Binary Tree	⇨
108	Convert Sorted Array to Binary Search Tree	⇨
110	Balanced Binary Tree	⇨
111	Minimum Depth of Binary Tree	⇨
121	Best Time to Buy and Sell Stock	⇨
122	Best Time to Buy and Sell Stock II	⇨
125	Valid Palindrome	⇨
144	Binary Tree Preorder Traversal	⇨
145	Binary Tree Postorder Traversal	⇨
215	Kth Largest Element in an Array	⇨
217	Contains Duplicate	⇨
238	Product of Array Except Self	⇨
242	Valid Anagram	⇨
278	First Bad Version	⇨
347	Top K Frequent Elements	⇨
355	Design Twitter	⇨
429	N-ary Tree Level Order Traversal	⇨
515	Find Largest Value in Each Tree Row	⇨
559	Maximum Depth of N-ary Tree	⇨
589	N-ary Tree Preorder Traversal	⇨
590	N-ary Tree Postorder Traversal	⇨
875	Koko Eating Bananas	⇨
1011	Capacity To Ship Packages Within D Days	⇨
2331	Evaluate Boolean Binary Tree	⇨

GeeksforGeeks

Problem ID	Solution	Problem Specs
convert-number-to-words	Convert a given number to words	⇨
minimize-sum-of-an-array-by-at-most-k-reductions	Minimize Sum of an Array by at Most K Reductions	⇨

CodeChef

Problem ID	Solution	Problem Specs
BRACKETS	Brackets	⇨
BROKPHON	Broken Telephone	⇨
EZSPEAK	Easy Pronunciation	⇨

Solutions By Category

Array

Platform	Problem ID	Solution	Problem Specs
LeetCode	1	Two Sum	⇨
LeetCode	13	Roman to Integer	⇨
LeetCode	32	Coin Change	⇨
LeetCode	35	Search Insert Position	⇨
LeetCode	49	Group Anagrams	⇨
LeetCode	55	Jump Game	⇨
LeetCode	66	Plus One	⇨
LeetCode	121	Best Time to Buy and Sell Stock	⇨
LeetCode	122	Best Time to Buy and Sell Stock II	⇨
LeetCode	215	Kth Largest Element in an Array	⇨
LeetCode	217	Contains Duplicate	⇨
LeetCode	238	Product of Array Except Self	⇨
LeetCode	242	Valid Anagram	⇨
LeetCode	347	Top K Frequent Elements	⇨
LeetCode	875	Koko Eating Bananas	⇨
LeetCode	1011	Capacity To Ship Packages Within D Days	⇨
GeeksforGeeks	convert-number-to-words	Convert a given number to words	⇨
CodeChef	BRACKETS	Brackets	⇨
CodeChef	BROKPHON	Broken Telephone	⇨
CodeChef	EZSPEAK	Easy Pronunciation	⇨

String

Platform	Problem ID	Solution	Problem Specs
LeetCode	3	Longest Substring Without Repeating Characters	⇨
LeetCode	12	Integer to Roman	⇨
LeetCode	13	Roman to Integer	⇨
LeetCode	20	Valid Parentheses	⇨
LeetCode	49	Group Anagrams	⇨
LeetCode	125	Valid Palindrome	⇨
LeetCode	242	Valid Anagram	⇨
GeeksforGeeks	convert-number-to-words	Convert a given number to words	⇨
CodeChef	BRACKETS	Brackets	⇨
CodeChef	EZSPEAK	Easy Pronunciation	⇨

Map

Platform	Problem ID	Solution	Problem Specs
LeetCode	1	Two Sum	⇨
LeetCode	3	Longest Substring Without Repeating Characters	⇨
LeetCode	12	Integer to Roman	⇨
LeetCode	13	Roman to Integer	⇨
LeetCode	49	Group Anagrams	⇨
LeetCode	355	Design Twitter	⇨

Set

Platform	Problem ID	Solution	Problem Specs
LeetCode	217	Contains Duplicate	⇨

Stack

Platform	Problem ID	Solution	Problem Specs
LeetCode	20	Valid Parentheses	⇨
LeetCode	94	Binary Tree Inorder Traversal	⇨
LeetCode	101	Symmetric Tree	⇨
LeetCode	144	Binary Tree Preorder Traversal	⇨
LeetCode	145	Binary Tree Postorder Traversal	⇨
LeetCode	589	N-ary Tree Preorder Traversal	⇨
LeetCode	590	N-ary Tree Postorder Traversal	⇨

Queue

Platform	Problem ID	Solution	Problem Specs
LeetCode	101	Symmetric Tree	⇨
LeetCode	102	Binary Tree Level Order Traversal	⇨
LeetCode	111	Minimum Depth of Binary Tree	⇨
LeetCode	429	N-ary Tree Level Order Traversal	⇨

Deque

Platform	Problem ID	Solution	Problem Specs
LeetCode	355	Design Twitter	⇨

Linked List

Platform	Problem ID	Solution	Problem Specs
LeetCode	2	Add Two Numbers	⇨
LeetCode	23	Merge k Sorted Lists	⇨

Priority Queue

Platform	Problem ID	Solution	Problem Specs
LeetCode	23	Merge k Sorted Lists	⇨
LeetCode	215	Kth Largest Element in an Array	⇨
LeetCode	347	Top K Frequent Elements	⇨
LeetCode	355	Design Twitter	⇨
GeeksforGeeks	minimize-sum-of-an-array-by-at-most-k-reductions	Minimize Sum of an Array by at Most K Reductions	⇨

Heap

Platform	Problem ID	Solution	Problem Specs
LeetCode	23	Merge k Sorted Lists	⇨
LeetCode	215	Kth Largest Element in an Array	⇨
LeetCode	347	Top K Frequent Elements	⇨
GeeksforGeeks	minimize-sum-of-an-array-by-at-most-k-reductions	Minimize Sum of an Array by at Most K Reductions	⇨

Tree

Platform	Problem ID	Solution	Problem Specs
LeetCode	94	Binary Tree Inorder Traversal	⇨
LeetCode	100	Same Tree	⇨
LeetCode	101	Symmetric Tree	⇨
LeetCode	102	Binary Tree Level Order Traversal	⇨
LeetCode	104	Maximum Depth of Binary Tree	⇨
LeetCode	108	Convert Sorted Array to Binary Search Tree	⇨
LeetCode	110	Balanced Binary Tree	⇨
LeetCode	111	Minimum Depth of Binary Tree	⇨
LeetCode	144	Binary Tree Preorder Traversal	⇨
LeetCode	145	Binary Tree Postorder Traversal	⇨
LeetCode	429	N-ary Tree Level Order Traversal	⇨
LeetCode	515	Find Largest Value in Each Tree Row	⇨
LeetCode	559	Maximum Depth of N-ary Tree	⇨
LeetCode	589	N-ary Tree Preorder Traversal	⇨
LeetCode	590	N-ary Tree Postorder Traversal	⇨
LeetCode	2331	Evaluate Boolean Binary Tree	⇨

Binary Tree

Platform	Problem ID	Solution	Problem Specs
LeetCode	94	Binary Tree Inorder Traversal	⇨
LeetCode	100	Same Tree	⇨
LeetCode	101	Symmetric Tree	⇨
LeetCode	102	Binary Tree Level Order Traversal	⇨
LeetCode	104	Maximum Depth of Binary Tree	⇨
LeetCode	108	Convert Sorted Array to Binary Search Tree	⇨
LeetCode	110	Balanced Binary Tree	⇨
LeetCode	111	Minimum Depth of Binary Tree	⇨
LeetCode	144	Binary Tree Preorder Traversal	⇨
LeetCode	145	Binary Tree Postorder Traversal	⇨
LeetCode	515	Find Largest Value in Each Tree Row	⇨
LeetCode	2331	Evaluate Boolean Binary Tree	⇨

Binary Search Tree

Platform	Problem ID	Solution	Problem Specs
LeetCode	108	Convert Sorted Array to Binary Search Tree	⇨

Depth-First Search

Platform	Problem ID	Solution	Problem Specs
LeetCode	94	Binary Tree Inorder Traversal	⇨
LeetCode	100	Same Tree	⇨
LeetCode	101	Symmetric Tree	⇨
LeetCode	104	Maximum Depth of Binary Tree	⇨
LeetCode	110	Balanced Binary Tree	⇨
LeetCode	111	Minimum Depth of Binary Tree	⇨
LeetCode	144	Binary Tree Preorder Traversal	⇨
LeetCode	145	Binary Tree Postorder Traversal	⇨
LeetCode	559	Maximum Depth of N-ary Tree	⇨
LeetCode	589	N-ary Tree Preorder Traversal	⇨
LeetCode	590	N-ary Tree Postorder Traversal	⇨
LeetCode	2331	Evaluate Boolean Binary Tree	⇨

Breadth-First Search

Platform	Problem ID	Solution	Problem Specs
LeetCode	101	Symmetric Tree	⇨
LeetCode	102	Binary Tree Level Order Traversal	⇨
LeetCode	111	Minimum Depth of Binary Tree	⇨
LeetCode	429	N-ary Tree Level Order Traversal	⇨
LeetCode	515	Find Largest Value in Each Tree Row	⇨

Math

Platform	Problem ID	Solution	Problem Specs
LeetCode	2	Add Two Numbers	⇨
LeetCode	69	Sqrt(x)	⇨

Dynamic Programming

Platform	Problem ID	Solution	Problem Specs
LeetCode	32	Coin Change	⇨
LeetCode	55	Jump Game	⇨
LeetCode	121	Best Time to Buy and Sell Stock	⇨
LeetCode	122	Best Time to Buy and Sell Stock II	⇨
LeetCode	238	Product of Array Except Self	⇨

Greedy

Platform	Problem ID	Solution	Problem Specs
LeetCode	55	Jump Game	⇨

Binary Search

Platform	Problem ID	Solution	Problem Specs
LeetCode	35	Search Insert Position	⇨
LeetCode	69	Sqrt(x)	⇨
LeetCode	278	First Bad Version	⇨
LeetCode	875	Koko Eating Bananas	⇨
LeetCode	1011	Capacity To Ship Packages Within D Days	⇨

Sort

Platform	Problem ID	Solution	Problem Specs
LeetCode	215	Kth Largest Element in an Array	⇨
LeetCode	347	Top K Frequent Elements	⇨